1. Field of the Invention
The present invention relates to computer-based tools for manipulating digital images. More specifically, the present invention relates to a method and an apparatus for dynamically refocusing a digital image to simulate changing the focus plane and the depth-of-field of a “virtual camera.”
2. Related Art
Dramatic increases in computational power in recent years make it possible to perform a wide range of sophisticated computational operations on digital images. In particular, there are presently a number of techniques for using three-dimensional information to produce images that create a feeling of three-dimensional depth.
Blur filters are sometimes used to selectively defocus an image (or parts of an image) to simulate defocus and change of focus, thereby creating a feeling of three-dimensionality. However, existing blur filters only approximate the physics behind defocus and change of focus operations and as a result often produce unrealistic looking results.
Warping techniques use stereo or multiple-view geometry to distort an image to create the effect of a camera moving through space. However, artifacts are often created during the warping process due to a sparse or imperfect warping mesh. Consequently, in practice it is hard to produce convincing three-dimensional results without hard work to establish a dense correspondence mesh of good quality.
Light-field techniques typically involve taking pictures with an array of 64 or more cameras and then building a large database representing all rays in three dimensions along with their associated colors. A light-field image can then be produced by performing a search through the large database of rays, which can be a very slow process. Furthermore, artifacts are often created due to not being able to represent rays that fall between cameras (see A. Isaksen, L. McMillan and S. Gortler, “Dynamic Reparameterized Light Fields,” Proceedings of SIGGRAPH 2000.)
Hence, what is needed is a method and an apparatus for using three-dimensional information to produce images that create a feeling of three-dimensional depth without the above-described problems.